John Chalmers

Validation of EuroSCORE II in a modern cohort of patients undergoing cardiac surgery.

OBJECTIVE We aimed to validate the new EuroSCORE II risk model in a contemporary cardiac surgery practice in the United Kingdom (UK). METHODS The original logistic EuroSCORE was compared to EuroSCORE II with regard to accuracy of predicting in-hospital mortality. Analysis was performed on isolated coronary artery bypass grafts (CABG; n = 2913), aortic valve replacement (AVR; n = 814), mitral valve surgery (MVR; n = 340), combined AVR and CABG (n = 517), aortic (n = 350) and miscellaneous procedures (n = 642), and the above cases combined (n = 5576). RESULTS In a single-institution experience, EuroSCORE II is a reasonable risk model for in-hospital mortality from isolated CABG (C-statistic 0.79, Hosmer-Lemeshow P = 0.052) and aortic procedures (C-statistic 0.81, Hosmer-Lemeshow P = 0.43), and excellent for mitral valve surgery (C-statistic 0.87, Hosmer-Lemeshow P = 0.6). EuroSCORE II is better than the original EuroSCORE, using contemporaneous data for combined AVR and CABG operations (C-statistic 0.74, Hosmer-Lemeshow P = 0.38). However, EuroSCORE II failed to improve on the original EuroSCORE model for isolated AVR (C-statistic 0.69, Hosmer-Lemeshow P = 0.07) and miscellaneous procedures (C-statistic 0.70, Hosmer-Lemeshow P = 0.99). EuroSCORE II has better calibration than the original EuroSCORE or the Society of Cardiothoracic Surgeons of Great Britain and Ireland (SCTS) modified EuroSCORE for cumulative sum survival (CUSUM) curves. CONCLUSIONS EuroSCORE II improves on the original logistic EuroSCORE, though mainly for combined AVR and CABG cases. Concerns still exist, however, over its use for isolated AVR procedures, aortic surgery and miscellaneous procedures. There is still room for improvement in risk modelling.

Long-term survival after coronary artery bypass surgery stratified by EuroSCORE

OBJECTIVES Coronary artery bypass grafting (CABG) is performed for symptoms and for prognostic reasons. The EuroSCORE is widely utilized as a pre-operative risk prediction tool. We evaluated our long-term survival figures based on EuroSCORE. METHODS A prospective database was retrospectively analysed and cross correlated with the UK strategic tracking service to evaluate survival after primary CABG. Patients were grouped based on their logistic EuroSCORE 0 to <5, 5 to <10, 10 to <15, 15 to <20, 20 to <25 and ≥25. RESULTS We analysed 13,337 primary cardiac procedures. A total of 9961 procedures had a logistic EuroSCORE of 0 to <5, 2041 of 5 to <10, 636 of 10 to <15, 281 of 15 to <20, 137 of 20 to <25 and 281≥25. Long-term survival is significantly affected by logistic EuroSCORE, P < 0.001. Patients with a logistic EuroSCORE <5% had significantly better initial survival and a lower rate of death over a 10-year period, P<0.001. Patients with a logistic score over 25 had a significantly worse 5-year survival, P<0.001. Logistic EuroSCORE was poor at predicting survival when >5 and <25. Cox multivariate regression and neuronal network analysis confirmed that the additional factors, diabetes, body mass index (BMI), post-operative myocardial creatinine kinase myocardial isoenzyme (CKMB) and left internal mammary artery (LIMA) usage, which are not incorporated in EuroSCORE significantly predict long-term survival. CONCLUSIONS Logistic EuroSCORE is a reasonable approximation for long-term survival after CABG, if the score is <5; however, its predictive capacity is limited due to the absence of LIMA usage, BMI, diabetes and CKMB in its calculation, all of which are significant factors affecting long-term survival.

Impact of chronic obstructive pulmonary disease severity on surgical outcomes in patients undergoing non-emergent coronary artery bypass grafting †

OBJECTIVES Although the association between chronic obstructive pulmonary disease (COPD) and adverse surgical outcomes has been previously demonstrated, the impact of COPD severity on postoperative mortality and morbidity remains unclear. Our objective was to analyse the prognostic implication of COPD stages as defined by the Global Initiative for Chronic Obstructive Lung Disease. METHODS Between September 1997 and April 2010, 13,638 patients undergoing first time isolated CABG were retrospectively reviewed, of whom 2421 patients were excluded due to lack of spirometry records or restrictive pattern on spirometry. The remaining 11,217 patients were divided into three groups: group 1 (including patients with normal spirometry and patients with mild COPD (FEV1/FVC ratio<70%, FEV1≥80% predicted), group 2 (moderate COPD: FEV1/FVC ratio<70%, 50%≤FEV1<80% predicted) and group 3 (severe COPD: FEV1/FVC ratio<70%, FEV1<50% predicted). Logistic regression was used to examine the effect of COPD severity on early mortality and morbidity, after adjusting for differences in patient characteristics. RESULTS Early mortality in the three groups was 1.4, 2.9 and 5.7% respectively (P<0.001). Similarly, a consistent trend of increasing frequency of postoperative complications with advanced COPD stage was noted. On multivariate analysis, severe COPD was found to be significantly associated with early mortality [adjusted OR, 2.31 (95% CI) (1.23-4.36)], P=0.01. CONCLUSIONS The severity of COPD as defined by spirometry can be a prognostic marker in patients undergoing CABG. Spirometric criteria may help refining currently used operative risk scores.

A need for speed? Bypass time and outcomes after isolated aortic valve replacement surgery

OBJECTIVES To determine in the modern era if cardiopulmonary bypass (CPB) time has a significant effect on postoperative morbidity, mortality and long-term survival in patients undergoing isolated aortic valve replacement (AVR) surgery. METHODS Analysis of a prospectively collected cardiac surgery database was performed. Uni- and multivariate analysis on the need of resternotomy for bleeding, mediastinal blood loss, intensive care unit (ICU) length of stay, hospital length of stay, in-hospital mortality and long- term survival was performed. Only patients with a cross-clamp time <90 min were analysed to exclude technical issues confounding the results. RESULTS A total of 1863 isolated first-time AVR procedures were analysed, with an in-hospital mortality rate of 2.4%. The rate of long-term follow-up achieved was 100%. Univariate analysis revealed that CPB time (minutes) had no significant effect on resternotomy (P = 0.5), creatinine kinase muscle-brain isoenzyme (CKMB) release (P = 0.8) and long-term survival (P = 0.06), but was significantly associated with mediastinal blood loss (P = 0.01), ICU length of stay (P = 0.02), hospital length of stay (P = 0.03) and in-hospital mortality (P < 0.001). Multivariate analysis identified that bypass time (min) was a significant factor associated with mediastinal blood loss (P < 0.001), ICU length of stay (P = 0.01), postoperative length of stay (P < 0.001) and in-hospital mortality (odds ratio [OR] 1.02, 95% CI 1.01-1.04, P = 0.01), but not long-term survival. Multivariate analysis identified that era of surgery had no significant effect on CKMB release (P = 0.2), mediastinal blood loss (P = 0.4) and in-hospital mortality (P = 0.9), but the latter era of this study was significantly associated with a reduced postoperative length of stay (P < 0.001), reduced ICU length of stay (P < 0.001), reduced need for resternotomy for bleeding (OR 0.62, 95% CI 0.41-0.94, P = 0.02) and improved long-term survival (hazard ratio 0.76, 95% CI 0.59-0.96, P = 0.02). Adjusting for era made no difference with respect to the above study findings. CONCLUSIONS Despite improvements over time with regard to morbidity, mortality and long-term survival, CPB time remains a significant factor determining mediastinal blood loss, ICU and hospital length of stay, and in-hospital mortality.

The long-term effects of developing renal failure post-coronary artery bypass surgery, in patients with normal preoperative renal function

OBJECTIVES Renal failure post-cardiac surgery is associated with an increased in hospital morbidity and mortality. We investigated the effect of new onset renal risk, injury or failure [risk, injury, failure, loss and end-stage kidney disease (RIFLE)] post-coronary artery bypass graft (CABG) on long-term survival, in patients with normal preoperative renal function. METHODS The effect of developing postoperative renal risk, injury or failure as defined by the RIFLE criteria on the long-term survival of patients undergoing isolated CABG with a normal renal function was studied. Two separate multivariate analyses were performed based on preoperative serum creatinine or glomerular filtration rate (GFR). Univariate, multivariate, interaction and confounding factor analyses were performed. RESULTS A total of 4029 isolated CABG patients were included in the study. 46.5% of patients had chronic kidney disease (CKD) stage 1 (GFR ≥90 ml/min/1.73 m(2)), 50.4% had CKD stage 2 (GFR 60-89 ml/min/1.73 m(2)) and 3.1% had CKD stage 3 (GFR 30-59 ml/min/1.73 m(2)) on admission, despite having a normal serum creatinine. The study group had a median follow-up of 3.6 years (95% CI 0-13.7). Renal risk, injury and failure were associated with a significantly reduced long-term survival (P < 0.001). In patients with normal preoperative serum creatinine, Cox regression analysis revealed that age (P = 0.026), preoperative creatinine (P =0.006) and logistic EuroSCORE (P < 0.0001) were significant factors in addition to the development of postoperative renal risk, injury or failure (P < 0.0001), with regard to determining long-term survival. A confounding factor analysis revealed that discharge creatinine (P = 0.0001) and discharge GFR (P = 0.0006) were significant determinants of long-term survival. In patients with a preoperative GFR >90 ml/min, Cox regression analysis revealed that diabetes (P = 0.004) sex (P = 0.019) and logistic EuroSCORE (P < 0.0001), were also significant factors in addition to the development of postoperative renal risk, injury or failure (P = 0.0001) with regard to determining long-term survival. A significant interaction between diabetes and the development of renal risk, injury or failure exists (P = 0.04). A confounding factor analysis revealed that discharge creatinine was a significant determinant (P = 0.0001) of long-term survival, and discharge GFR was not. CONCLUSIONS Despite being a biochemically reversible process, the development of renal risk, injury and failure as defined by the RIFLE criteria post-cardiac surgery in patients with a normal preoperative renal function is associated with a significantly worse long-term outcome.

Outcomes and predictors of prolonged ventilation in patients undergoing elective coronary surgery

OBJECTIVES Despite the seriousness of prolonged mechanical ventilation (PMV) as a postoperative complication, previously proposed risk prediction models were met with limited success. The purpose of this study was to identify perioperative variables associated with PMV in elective primary coronary bypass surgery. PMV was defined as the need for intubation and mechanical ventilation for >72 h, after completion of the operation. METHODS Between April 1997 and September 2010, 10 ,977 consecutive patients were retrospectively reviewed. A series of two multivariate logistic regression analyses were carried out to identify preoperative predictors of prolonged ventilation and the impact of operative variables. RESULTS PMV occurred in 215 (1.96%) patients; 119 (55.3%) of these underwent tracheostomy. At multivariate analysis, predictors included NYHA higher than class II (odds ratio [OR], 1.77; 95% confidence intervals [CI], 1.34-2.34), renal dialysis (OR, 5.5; 95% CI, 2.08-14.65), age at operation (OR, 1.04; 95% CI, 1.02-1.06), reduced FEV(1) (OR, 0.99; 95% CI, 0.98-0.99), body mass index >35 kg/m(2) (OR, 1.73; 95% CI, 1.14-2.63). On serial logistic regression analyses, operative variables added little to the discriminatory power of the model. Kaplan-Meier survival curves showed reduced survival among PMV patients (P < 0.001) with an improved survival in the tracheostomy subgroup. CONCLUSIONS PMV after coronary bypass is associated with a reduction in early and mid-term survival. Risk modelling for PMV remains problematic even when examining a more homogenous lower risk group.

Red cell distribution width and coronary artery bypass surgery

OBJECTIVES The red cell distribution width (RDW) has been identified as an independent risk factor with regard to prognosis in patients with coronary artery disease with or without heart failure. We sought to investigate the role of RDW in patients undergoing isolated coronary artery bypass graft surgery (CABG). METHODS Analysis of consecutive patients on a validated prospective cardiac surgery database was performed for patients undergoing isolated CABG. Univariate and multivariate analysis was performed for in hospital mortality, long-term survival, length of hospital stay, length of intensive care unit stay and creatinine kinase muscle-brain (CKMB) release. RESULTS Overall mortality was 2.1% for all cases, N = 8615. Median follow up was 5.8 years. Univariate analysis demonstrated that the RDW has a significant effect on CKMB release, P = 0.001, in-hospital mortality, P < 0.0001, and long-term survival, P < 0.0001, but no significant effect on the ITU length of stay, P = 0.9, or hospital length of stay, P = 0.2. Multivariate analysis revealed that the RDW was a significant factor determining in-hospital mortality and long-term survival, but had no significant effect on CKMB release, ITU or hospital length of stay. Confounding factor analysis revealed that in the absence of anaemia, the RDW was still a significant factor determining in-hospital mortality and long-term survival. CONCLUSIONS The RDW is a significant factor determining in-hospital mortality and long-term survival in patients undergoing isolated CABG. The mechanism of association requires further study.

Long-term survival of patients with pulmonary disease undergoing coronary artery bypass surgery.

OBJECTIVES We sought to investigate the long-term survival of patients with obstructive, restrictive and chronic obstructive pulmonary disease (COPD) as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD). METHODS A prospective database was retrospectively analysed and cross-correlated with the UK strategic tracking service to evaluate survival after primary coronary artery bypass grafts (CABG). Univariate and multivariate Cox regression analyses were performed. Three separate multivariate analyses were performed: COPD GOLD criteria for obstructive and/or restrictive lung disease, forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and the FEV1/FVC ratio to investigate the effect of FEV1 and FVC individually. RESULTS We analysed 13 337 primary CABG procedures. The median follow-up was 7 years. Univariate analysis demonstrated that obstructive (P < 0.0001), restrictive (P < 0.0001) and mixed obstructive and restrictive pulmonary disease (P < 0.0001), and COPD as defined by the GOLD criteria (P < 0.0001), are all significant factors determining long-term survival. Cox regression analysis identified age, diabetes, moderate LV, poor LV, peripheral vascular disease, dialysis, left internal mammary artery (LIMA) usage, EuroSCORE, cardiopulmonary bypass and creatinine kinase muscle-brain isoenzyme as significant factors in addition to pulmonary disease that determine long-term survival. Moderate and severe COPD defined by GOLD criteria were significant factors determining long-term survival, but mild COPD had no significant effect. Obstructive and restrictive lung disease were both significant factors determining long-term survival. Restrictive lung disease, however, carried a greater prognostic significance (higher hazard ratio 2.2 vs 1.6) than obstructive. LIMA utilization in patients with COPD was not associated with an increased intensive care unit stay, re-intubation rate or in-hospital mortality rate. CONCLUSIONS Pulmonary disease is a significant factor determining long-term survival. Patients with severe COPD still have a relatively good long-term survival and should not be denied surgery. LIMA utilization in patients with COPD results in a significantly increased long-term survival, without an increased intensive care unit stay, re-intubation rate or in-hospital mortality rate.

Is single-unit blood transfusion bad post-coronary artery bypass surgery?

OBJECTIVES Publications in the surgical literature are very consistent in their conclusions that blood is dangerous with regard to in-hospital mortality, morbidity and long-term survival. Blood is frequently used as a volume expander while simultaneously increasing the haematocrit. We investigated the effects of a single-unit blood transfusion on long-term survival post-cardiac surgery in isolated coronary artery bypass grafting patients. METHODS A prospective single-institution cardiac surgery database was analysed involving 4615 patients. Univariate, multivariate stepwise Cox regression analysis and propensity matching were performed to identify whether a single-unit blood transfusion was detrimental to long-term survival. RESULTS Univariate analysis revealed that blood was significantly associated with a reduced long-term survival even with a single-unit transfused, P = 0.0001. Cox multivariate regression analysis identified age, ejection fraction, preoperative dialysis, logistic EuroSCORE, postoperative CKMB, blood transfusion, urgent operative status and atrial fibrillation as significant factors determining long-term survival. When the Cox regression was repeated with patients who received no blood or only one unit of blood, transfusion was not a risk factor for long-term survival. An interaction analysis revealed that blood transfusion was significantly interacting with preoperative haemoglobin levels, P = 0.02. Propensity analysis demonstrated that a single-unit transfusion is not associated with a detrimental long-term survival, P = 0.3. CONCLUSIONS Cox regression and propensity matching both indicate that a single-unit transfusion is not a significant cause of reduced long-term survival. Preoperative anaemia is a significant confounding factor. Despite demonstrating the negligible risks of a single-unit blood transfusion, we are not advocating liberal transfusion and would recommend changing from a double-unit to a single-unit transfusion policy. We speculate that blood is not bad, but that the underlying reason that it is given might be.

Does avoidance of cardiopulmonary bypass confer any benefits in octogenarians undergoing coronary surgery

OBJECTIVES There remain concerns about hospital outcomes in octogenarians being referred for coronary artery bypass grafting (CABG). Avoiding the use of cardiopulmonary bypass (CPB) may be an attractive option to improve early outcomes in this group of patients. METHODS Between April 1997 and March 2010, 343 consecutive patients aged 80-89 years received isolated first time CABG. We used logistic regression to develop a propensity score for off-pump group membership and then performed a propensity matched analysis comparing off-pump (n=107) to on-pump (n=107) groups for early mortality and morbidity. All analysis was performed retrospectively. RESULTS Preoperative patient characteristics were comparable in both groups, with mean age 82.0 years (80.6-83.7 years) and logistic EuroSCORE 9.9 (6.1-19.5) in the on-pump group compared to 81.6 (80.7-83.2) and 8.5 (5.3-15.7) in the off-pump group (P=0.96, P=0.23, respectively). Postoperatively, in-hospital mortality was 6.5% in the on-pump group compared to 4.7% in the off-pump group (P=0.55). Postoperative complications showed no statistically significant difference between the two groups. However, off-pump was associated with a shorter mechanical ventilation and intensive care unit (ICU) stay and less use of inotropes. CONCLUSION In our experience, avoiding CPB was not associated with a statistically significant reduction in early mortality, myocardial infarction or stroke rates. It was only associated with a shorter postoperative ventilation and ICU stay and less use of inotropes.